Gripper



July 30, 1940. A. F. PAGEL GRIPPER Filed Dec. 14, 1958 2 Sheets-Sheet l hzkzoiiaf Z @(QMZ/La A. F. PAGEL 2,209,630 H July 30, 1940.

' GRIPPER Filed Dec. 14, 1938 2 Sheets-Sheet 2 j Albert-F. Pagel,

"'GRlPPER Park Ridge, 111., assignor to PATENT crews a xSignode Steel Strapping Company, Chicago, I 111., a. corporation of Delaware Application December 14, 1938, Serial No. 245,628

4. Claims. (01. .254- -51) My invention relates to grippers.

It is particularly applicable" to and will be illustrated and explained as embodied in a gripper especially adapted for use in'a' tool for tensioning steel ribbon-like strap looped about bundles; consisting of packages or groups of packages; the endsof the binder loop are overlapped one over the other or superposed relative to the package surface and after application of the desired tension these superposed loop ends are secured together in any suitable manner to'render the tight package encircling loop permanent for the purpose of sealing or securing or reinforcing the packages or binding them together.

Heretofore in such tools the relatively movable members between which the ends of the strap are held have been positioned to engage opposite strap surfaces when brought together to grip and anchor the strap. This arrangement made it necessary to position one gripper member beneath the strapi. e., between the strap and the bundle being boundwhile the, other was above or at the outer side of the strap. And, because the gripper member located'beneath the strap (1. e., the inner gripper member) was required not only to withstand its share of the pull of the strap during the 'tensioning operation, but also to resist the thrust of the companion or complementary outer gripper member to'insure adequate grip upon the strap, the inner gripper member had to be quite thick and bulky. Frequently the inner gripper member formed part of the foot of the tool and then, in order to give the tool adequate support uponthe bundle, it was dlesresulted in relative looseness of the binder strap loop when the tool was removed. Second, the tension produced in, the strap tended to bind the inner gripper to the bundle, making removal of the tool relatively difficult.

One of the objects of the present invention is to provide an improved method of tensioning flat ribbon-like metallic package-binder strap.

A further object is to provide an improved strap gripper particularly adapted for package binding tools,a gripper which will overcome the dimculties heretofore mentioned.

Another object is to provide a gripper that engages and holds the strap by a clamping'action against its edges, rather than against its surfaces, thereby eliminating the necessity for providing a relatively large member interposed: between the strap and the bundle. r

Other objects and advantages will hereinafter appear.

The invention will be shown and described as embodied in a strap tensioning tool of the windlass type, although it is not limited to use in this type of tool. I

In the accompanying drawingst Fig. 1 is a side elevation of a tool in strap tensioning position on a package; I I

Fig. 2 is an'enlarged'bottom plan of the tool with part of the frame broken away;

Fig. 3 is an enlarged top plan with the'gripper open to receive'the strap, a part of .the frame being broken away;'

Fig. 4 is a similar View with the gripper closed in strap grippingposition;

Fig. 5 is a section on the line 5--5 of Fig. '4, and

Fig. 6 is a section onthe line 6---fi of Fig. 3. The tensioning tool in which the invention is embodied has a frame including a flat base I0 whichis reduced in width and elongated at the rear to form a handle H and two upstanding parallel flanges i2 and I3. In operation the base rests upright upon the bundle l5. In the tool chosen to illustrate'the invention one end lta of the package-encircling binder strap 15 is pulled by being wound upon the-periphery of a rotatable slotted Windlass head I! and the other end I61) of the strap is grippedand anchored by my improved gripper.

Since the Windlass is shown merely to complete one typical form of tensioning tool and constitutes no essential part of the present invention, its details are not all illustrated and it will be only briefly described. In general it includes a shaft 20, journaled in the flanges l2 and i3, that car rice the enlarged slotted head i! at one end and is held in place by a nut 2i, This'shaft is provided with a ratchet 22, the teeth of which are engaged by a holding pawl'zcarried by'the frame and by a spring-biased actuating pawl (not shown) mounted within the head 24 of a tensioning handle 25, which handle is adapted to be manipulated in a plane lying in the plane of the strap loop' and perpendicular to the package surface on which the tool rests. The actuating pawl and handle may be arranged, for example, as shown in Seagren Patent No. 1,912,045. In'

operation the extremity of the strap end Elia and create the desired tension in the strap loop encircling the package.

The strap edge gripper for anchoring the op posite loop-end of the strap includes, in general,

a fixed gripper member 30 and a complementary movable gripper member 3|. The active faces of these two gripper members or jaws are arranged so as to receive the strap flatwise between them when they are in separated or open position, to move toward each other in the fiatwise plane of the strap, and to engage the edges of the strap and clamp the strap edgewise between them when they are caused to approach each other to assume gripping position.

Stationary gripper 30 may be in the form of a hardened steel insert or plate 32 attached to the tool base ID by screws 33. Its active edge may be toothed or otherwise roughened to increase its gripping action upon the strap edge. The movable gripper 3| may be in the form of a similar plate 34 attached by suitable means, such as screws 35, to the end of a sliding bar 38. Bar 38 is adapted to slide in a guideway in the tool base and carries a gripper actuating lever 39 at the end opposite the movable gripper.

Gripper actuating lever 39 is pivotally attached to bar 38 by a screw 40 and has its forward end formed into a cam 4| which is adapted to act against one side of the tool base. When the gripper actuating handle is moved to a position substantially perpendicular to the tool base so as to bring the low portion of cam 4i facing the base, as shown in Figs. 2 and 3, and the bar 38 is shoved through the base until cam 4! strikes the base, the jaws or gripper members are separated to fully open position. In this condition the strap end l6b may be trained between the jaws or gripper members.

When the strap is in position between the gripping members, the slide may be moved by rotating the gripper actuating handle 39 toward the position shown in Figs. 4 and 5 which, through the action of cam 4| upon the side of the tool base, causes the slide to be moved toward the right as viewed in Fig. 3, to cause the movable gripper member to approach the stationary gripper member in the flatwise plane of the strap, and to cause the strap to be gripped edgewise between t the gripper members to anchor it. Thereafter the rotation of the Windlass head, as previously explained, causes the strap loop encircling the package to be tensioned upon the package to the desired degree.

The anchorage edgewise grip upon the strap end lBb may be retained during the tensioning operation by the operator holding the gripper actuating handle 39 in such position that the thrust of the jaws or gripper members upon the strap edges is sufiicient to prevent slippage. A position of the gripper actuating handle near to and about parallel with the elongated base handle I I when the tool is gripping makes it easy for the operator to retain the grip during the tensioning operation. After the binder loop has been tensioned to the desired amount, its overlapping ends may be joined together in any suitable manner to render the loop permanent.

The steel strapping generally used in package b nding is ordinarily sufliciently rigid or resistant to longitudinal buckling so that, unless the width is relatively great, it will withstand the edgewise clamping action or thrust of the grippers and will not be transversely deformed to weaken the gripping action upon its edges. If, however, the strap is relatively so wide or possesses so little rigidity or resistance to longitudinal buckling that the edgewise clamping action of the grippers unduly tends to deform it, this tendency may be counteracted by so reducing the clearance 42 between the bar 38 and the top surface of the strap that, should the strap tend to buckle outwardly, it will strike the bar and the reaction of the bar will limit the amount of buckling so as to insure a good edgewise grip. Ordinarily the bundle will sufi'iciently counteract any tendency of the strap to buckle inwardly.

By thus providing a gripper which does not require between the strap and bundle a member large and heavy enough to serve as an anvil or abutment against which the strap must be forcefully pushed and held in order to prevent movement, the previously mentioned disadvantages of such a construction are overcome.

Having thus illustrated a typical embodiment and explained the nature of my invention, what I vclaim and desire to secure by United States Letters Patent is as follows:

1. A gripper for holding a package binder strap comprising a pair of relatively movable gripper members for clamping the strap edgewise between them, the gripper members being positioned to engage opposite edges of the strap and the relative movement between them being toward and away from-the strap in the flatwise plane of the strap, and means for engaging the strap flatwise between the gripper members to prevent the strap buckling under the edgewise pressure exerted thereon by the gripper members.

2. The method of tensioning flat ribbon-like metallic package-binder strap looped about a package and with its end portions overlapped flatwise which consists in gripping at least one end portion of the strap loop by engagement with only its edges to anchor the same while the said end portion of the strap is maintained in substantial contact with the package, and pulling the other end portion of the loop to shrink and tension the strap about the package.

3. The method of tensioning fiat ribbon-like metallic package-binder strap looped about a package and with its end portions overlapped flatwise which consists in gripping at least one end portion of the strap by engagement and with pressure exerted only upon its edges to anchor the same while the said end portion of the strap is maintained in substantial contact with the package, supporting the strap against buckling intermediate the edgewise applied gripping forces, and pulling the other end portion of the loop to shrink and tension the strap about the package.

4. A tensioning tool for tensioning fiat ribbonlike metallic strap looped flatwise about a package and the like and with the ends of the loop overlapping one above the other relative to the adjacent package surface, said tool being of the type having a frame for resting upright on the package being bound, a gripper for holding one end of the strap loop and means for exerting a pull on the other end of the strap loop, and an operating handle movable in a plane parallel to the plane of the strap loop about the package and perpendicular to the surface of the package on which the frame rests, characterized by the fact that said gripper comprises two jaws relatively movable in a plane parallel to the surface of the package on which the frame rests so as to engage opposite edges of the flat strap and hold the same by edge-clamping action.

ALBERT F. PAGEL. 

